This is a nice little MUA for Unix/X11 based on the GTK+? (1.x series) widget set. It's simple, fairly quick, and JustWorks? (in particular it doesn't need, but can use, an external MTA).
Another major advantage (from my AntiBloat perspective) is that it doesn't depend on the assorted GNOME libraries, a GTK+? installation is all that is required.
does it do imap? -- 
PerryLorier
Yes, Sylpheed does support IMAP. I can't tell you if it has a good implementation, since I don't have any experience with it, but I haven't heard anything bad about it.
2 pages link to Sylpheed:
lib/main.php:944: Notice: PageInfo: Cannot find action page
http://sylpheed.good-day.net/